This invention relates to missile systems, and, more particularly, to the launching apparatus for a tube-fired missile.
Hand-carried missiles such as antitank or antiaircraft missiles are commonly stored and carried in a tubular launcher. When the missile is to be fired, the operator deploys a sight and a controller such as a handgrip trigger mechanism. To fire the missile, two distinct steps are required. In the first step, the power supply, sensor (if any), and guidance systems of the missile are activated. This activation is required because the power supply within the missile is typically a battery which is inert until activated, so that the missile may be stored for long periods of time prior to use without losing battery power. In the second step, performed after the first step is complete and the missile is active, a firing command is sent to the missile to cause its rocket motor to fire.
The inventor has recognized some shortcomings in the present launcher systems. First, although the power supply within the missile is typically normally inert and becomes activated only upon the firing of a squib, the power supply within the launch tube, which powers the signals sent to the missile, is a conventional battery which may drain or otherwise become inoperable during extended periods of storage. Battery checks of the launcher battery and replacement as necessary are therefore required for such launcher/missile systems which have been stored for a period of time. If the battery in the launcher is found to be inoperable and no replacement is readily available, the missile and launcher are inoperable.
A second problem is that the activation and firing signals are conveyed from the launcher to the missile through an umbilical which requires a secure electrical and physical connection to convey the signals, but also must have a quick and complete physical disconnection when the missile leaves the launch tube. If the electrical connection is not present, the activation and firing signals never reach the missile. The connection cannot be fully sealed, so that electrical interconnect problems may arise due to long-term corrosion effects and the like. Moreover, if the disconnection does not occur properly as the missile leaves the launch tube, the flight path of the missile may be altered so that the target is missed.
Solutions to both of these problems are needed, so as to improve the reliability of missile systems. The present invention fulfills this need, and further provides related advantages.
The present invention provides a missile system having a launcher and which may also include the missile itself. The launcher includes a self-contained pulse power source which does not utilize a battery. The launcher therefore has an indefinitely long storage life without the risk of a decline in capability. The electrical communication of the activation and firing signals from the launcher to the battery is made by a non-contacting, reliable, and secure technique. There is no concern with the long-term degradation of electrical contacts and with disconnection failures, as there is with an umbilical. The launcher power source is much less affected by environmental extremes such as high or lower temperatures, than is a conventional battery. The launcher and missile may each be made in a sealed form that resists the intrusion of external corrosion and the like into their interiors during storage. The maintainability of the launcher and the missile are thereby substantially improved, with reduced numbers of potential failure points and mechanisms, and a lower expected mean time between failures (MIBF).
In accordance with the invention, a missile system comprises a missile launcher including a pulse power source. The pulse power source comprises a piezoelectric crystal, an electrical contact to the piezoelectric crystal, and an actuatable source of a mechanical force disposed in operable relationship with the piezoelectric crystal.
The actuatable source of mechanical force preferably includes a hammer movable from a first position remote from the piezoelectric crystal to a second position in contact with the piezoelectric crystal. The force required to accomplish the movement may be provided from any operable source, but is preferably a spring biasing the hammer toward the second position with a biasing force. The actuatable source also includes a restraint holding the hammer in the first position against the biasing force of the spring, and a hammer release connected to the restraint to controllably release the restraint, thereby allowing the hammer to strike the piezoelectric crystal responsive to the biasing force of the spring. When the hammer strikes the piezoelectric crystal, there is a pulse of electrical energy whose voltage and amperage are established by the physical size of the crystal. The first pulse, which must be of relatively large amperage, is the activation pulse to activate the squib charge of the previously inert battery of the missile and otherwise bring the missile to an activated state. Other sources of force may be used, such as, for example, a cartridge that is fired by the hammer fall.
A second pulse is required to fire the engine of the missile. To produce a second, distinct pulse, it is preferred to provide a second piezoelectric crystal, a second electrical contact to the second piezoelectric crystal, and a second actuatable source of a second mechanical force disposed in operable relationship with the second piezoelectric crystal. The second actuatable source is preferably of the same hammer type as discussed previously. When the second hammer is released, it strikes the second piezoelectric crystal and produces the second, firing pulse. Other techniques for providing the second pulse may be used, such as, for example, an electrical tap of the first piezoelectric crystal and a second operation of the first hammer, or a delay circuit operating from the first pulse.
No battery is used in the launcher (although there typically is a battery in the missile itself). The energy of the electrical actuation and firing pulses is converted from mechanical force to electrical amperage by the piezoelectric crystal(s). For extreme long-term storage, there is the possibility of the biasing spring(s) losing the spring force by a creep mechanism, but this possibility may be minimized by maintaining the strain in the spring(s) well below the elastic limit or avoided entirely by leaving the spring(s) in the untensioned state during storage and providing a manual cocking mechanism that must be operated prior to activation and firing of the missile.
The activation and firing pulses are desirably transmitted from the launcher to the missile by a noncontacting approach. Preferably, the electrical pulse from the piezoelectric crystal is transmitted to a primary induction coil in the launcher, which excites a responsive electrical pulse in a secondary induction coil in the missile. The primary and secondary induction coils may be of any operable configuration. However, the launcher is typically a hollow, generally cylindrical tube which receives the generally cylindrical missile therein. The primary induction coil is most conveniently provided as one or more turns of electrical conductor wound circumferentially in the launch tube, and the secondary induction coil is one or more turns of electrical conductor wound circumferentially around the fuselage of the missile, in facing relation to the primary induction coil. With this approach, there is no physical connector required, and no concern with failure of the disconnect as the missile leaves the launcher. Moreover, the launcher body and the missile fuselage may be more completely sealed against intrusion of corrosives, dirt, and the like, than is possible with a plug-type connector, an important consideration in view of the increased longevity of the launcher with the piezoelectric pulse source.
The piezoelectric pulse source and the induction connection approaches are preferably used together. However, the piezoelectric pulse source may be used with other types of connector techniques, such as an umbilical plug connector, and the induction transmission approach may be used with other pulse sources such as battery-based sources.
The present invention provides a missile launch system of increased life and improved reliability. Other features and advantages of the present invention will be apparent from the following more detailed description of the preferred embodiment, taken in conjunction with the accompanying drawings, which illustrate, by way of example, the principles of the invention. The scope of the invention is not, however, limited to this preferred embodiment.